Glossary - alphabet order - "M"

Maximum drive level

This is the highest drive level at which the crystal unit can operate normally. When a current or charge exceeding this level is applied, degradation of characteristics or physical damage may occur. Special caution is required for tuning fork crystal units.

Maximum supply voltage

This is the maximum rated value for the voltage supplied to a power supply pin. If a voltage exceeding this value is applied, degradation of characteristics or physical damage may occur.

Mechanical processing

This is defined as the use of mechanical methods to create a shape. For crystal devices, mechanical processing has long been used to create tuning fork shapes from crystals. Note with caution that these products differ in terms of dimensions and characteristics from later products that have been fabricated using photolithography processing.

Metal material are used for the package of crystal units/crystal oscillators. Although metal materials have long been used in crystal products, plastic package and ceramic packages are now also used as SMD packages, so these packages are referred to separately as metal can packages. Metal can packages are still the main type of package used as DIP packages. A metal can package with a 14-pin DIP configuration is called a full-size package while one with an 8-pin DIP configuration is called a half-size package.

Mirror

It is a device that reflects an incident light beam for changing it's path. The mirror is classified into two categories; a dichroic mirror and a leakage mirror. The dichroic mirror changes paths of light beams including two wavelengths. The leakage mirror partially transmits such light beams.

The equivalent electrostatic capacitance component in a crystal unit at a series resonance frequency, motional capacitance is equivalent to strain energy. This capacitance is indicated as C1 in the equivalent circuit diagram at right.

Motional resistance

Crystal unit's equivalent circuit

This corresponds to internal equivalent resistance component in crystal oscillator, and is equivalent to the oscillation loss. This can be regarded as a reference for the ease of oscillation. This is also called equivalent serial resistance, and is shown as R1 in the equivalent circuit diagram at right.

Mounting

This refers to the mechanical fixation and getting electrical connection of a crystal chip into a package. Generally, the end of the crystal chip that is minimum impact for vibration is chosen as a fixation area, but since the mechanical strength (adhesion area) conflicts with the crystal chip's characteristics, various fastening methods, adhesives, and structures have been developed recently for small packages.

Structure of AT crystal unit

Mounting of tuning tork crystal chip

Multiplying circuit

Multiplying circuits are used to generate a high-frequency clock from a reference clock frequency.